Talc, soapstone

A number of nonmetallic mineral deposits are formed during metamorphism as a result of recrystallisation. Important among these are graphite, asbestos, talc, soapstone and pyrophyllite, kyanite, sillimanite, and semi precious stones like garnet and emery. 

Another common alteration involves the replacement of serpentine by chlorite, resulting in a rock composed solely of chlorite and magnetite. Further replacement by talc or talc-carbonate will result in a talc-chlorite (-carbonate) soapstone. Other alterations can result in the formation of tremolite-talc or chlorite-tremolite-talc soapstones. 

Smith, J., "Talc, Soapstone and Related Stone Deposits in Virginia, Va. 

Mg3Si4O10(OH)2or3MgO 4SiO2 H2O. A natural hydrous magnesium silicate. Compact, massive varieties may be called steatite in distinction from the foliated varieties, which are called talc. Soapstone is an impure variety of steatite. 

Typical fillers carbon black, calcium carbonate, dolomite, clays, calcinated clays, talc, soapstone, zinc oxide, filmed silica, borates, iron oxide, zinc oxide, magnesium carbonate, pulverized polyurethane foam, barium and strontium ferrites, magnesium aluminum silicate, nylon fibers, quartz in EMI shielding field silver plated aluminum, silver plated nickel, silver coated glass spheres, silver plated copper, silver, nickel and carbon black... 

Synonyms/Trade Names Massive talc. Soapstone silicate. Steatite... 

Magnesium silicates group Talc Soapstone Patton (1973e)... 

Talc. Talc (qv) [14807-96-6] (Cl Pigment White 26, Cl No. 77019), is finely powdered, native, hydrous magnesium sihcate, 3MgO 4Si02 H20 (soapstone) sometimes containing a small amount of aluminum siUcate. It is produced ia many parts of the world, including France, Italy, India, and the United States. 

Soft Materials (1) Talc, dried filter-press cakes, soapstone, waxes, aggregated salt ciystals (2) gypsum, rock salt, ciystahine salts in gener, soft coal (3) calcite, marble, soft limestone, barites, chalk, brimstone. 

Talc and Soapstone Generally these are easily pulverized. Certain fibrous and foliated talcs may offer greater resistance to reduc tion to impalpable powder, but these are no longer produced because of their asbestos content. 

Talc, unlike Che micas, consists of electrically neutral layers without the interleaving cations. It is valued for its softness, smoothrtess and dry lubricating properties, and for its whitertess, chermcal inertness and foliated structure. Its most important abdications are in ceramics, insecticides, paints and paper manufacture. The more familiar use in cosmetics and toilet preparations accounts for only 3% of world production which is about 5 Mt per annum. Half of this comes from Japan and the USA. and other major producers are Korea, the former Soviet Union, France and China. Talc and its more massive mineral form soapstone or steatite arc widely distributed throughout the world and many countries produce it for domestic consumption either by open-cast or underground mining. 

Talk-pulver, n. talcum powder, -schiefer, m. talc schist, talcose slate, slaty talc. >spat, m. magnesite, -stein, m. soapstone, steatite. Talkum, n. talc, talcum. 

A bar of talc feels like a bar of soap which is why it is often called soapstone. Its exceptional softness (it is the softest of the Mohs minerals) is a direct result of its unusual crystal structure. This consists of sheets of silicate tetrahedra without metal ions between the sheets. Thus the sheets are bonded only by London polarization forces. The latter are particularly weak because silicate tetrahedra have relatively small polarizabilities. 

Soapstone is a soft metamwphk rock without precise mineralogical definition composed mainly of talc, dolomite, and actinolite talc is mined as soapstone, hut some forms of soapstone have as little as 50% talc. 

Toxicology. The fibrous talc in soapstone dust causes fibrotic pneumoconiosis an increased incidence of cancer of the lungs and pleura has been reported. 

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